Freestanding stair assemblies are well known in the art, the most common being the spiral staircase having interengageable risers on each of which a stair tread is secured. Such spiral staircases often require a central vertical pole to which each tread, or each preformed riser assembly is secured. Such systems are complex and expensive. Other systems exist which avoid the use of a central stabilizing pole, such systems depending on the integrity of the interengagement between vertically adjacent riser members to achieve structural rigidity. An example of such an assembly is found in Canadian Pat. No. 1,005,964 (Hamm) issued Mar. 1, 1977. Another system which dispenses with a vertical pole is found in U.S. Pat. No. 3,491,498 (Hughes, Jr.), issued Jan. 27, 1970 which shows links having serrated top and bottom edges and a sloped cylindrical wall. The serrated edges are intended to grip the stair tread although it is necessary to provide a hole in each tread for receipt of a cable which is stretched to apply a compressive load to the tread and riser assembly. Both of the aforementioned systems are expensive to produce and require considerable skill to assemble. Since such systems are aimed at the home handyman as well as at the general contractor it is desirable to provide a system which is simple to produce and assemble and which is also inexpensive at the retail level.